Osteoarthritis (OA) is a widespread and increasingly prevalent disorder impairing quality of life for tens of millions of patients. Evidence from study of human OA and several animal OA models, suggests that during OA progression a recapitulation of chondrocyte phenotypic maturation occurs resembling embryonic endochondral ossification. In the prior funding period we identified a number of phenotypic maturational characteristics, which are expressed in OA cartilage, including PTHrP, MMP9, MMP13, Ihh, and BMP6. Articular chondrocytes are extremely refractory in culture to induction of this maturational cascade and are relatively unresponsive to growth factors. However, treatment with azacytidine, which allows demethylation of suppressed genes, induces the normal cascade of chondrocyte maturation, resulting in expression of type X collagen and other hypertrophic markers. Study of the specific signaling pathways involved have implicated a Smad ubiquitinating ligase, Smurf2, as a potential key regulatory step in shifting signal dominance from the TGF-beta to the BMP Smad pathway, leading to chondrocyte maturation. Smurf2 was found to be expressed in human OA but not normal articular cartilage, and is induced by azacytidine treatment in culture. Smurf2 stimulation or over-expression leads to Smad2 and Smad3 degradation, down-regulation of TGF-beta signaling, and up-regulation of BMP signaling. This is sufficient to initiate the entire cascade of chondrocyte maturation and hypertrophy in culture.
Specific Aim (1): An investigation of the role of Smurfs in regulation of chondrocyte phenotype in vitro will utilize articular and growth plate chondrocytes in culture to study Smurf1 and 2 effects on Smad signaling and chondrocyte phenotype. The regulation of Smurf expression by relevant growth factors and cytokines will also be studied.
Specific Aim (2): Investigation of the role of Smurf2 in chondrocyte maturation and OA in vivo will use a chick limb bud system to analyze effects of Smurf2 on chondrogenesis and maturation during development. A transgenic murine model of cartilage targeted Smurf2 over-expression will be created, and viral transduction of chondrocytes in vivo will be utilized to determine if Smurf2 over-expression can induce, or its inhibition suppress, OA. Finally, the expression of Smurf1 and Smurf2 in human normal and OA cartilage will be examined. These studies should provide a comprehensive picture of the function of Smurfs in regulating normal and OA cartilage phenotype.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
2R01AR045700-05A1
Application #
6722484
Study Section
Oral Biology and Medicine Subcommittee 1 (OBM)
Program Officer
Tyree, Bernadette
Project Start
1999-01-15
Project End
2009-03-31
Budget Start
2004-06-11
Budget End
2005-03-31
Support Year
5
Fiscal Year
2004
Total Cost
$277,200
Indirect Cost
Name
University of Rochester
Department
Orthopedics
Type
Schools of Dentistry
DUNS #
041294109
City
Rochester
State
NY
Country
United States
Zip Code
14627
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Holz, Jonathan D; Beier, Eric; Sheu, Tzong-Jen et al. (2012) Lead induces an osteoarthritis-like phenotype in articular chondrocytes through disruption of TGF-? signaling. J Orthop Res 30:1760-6
Sampson, Erik R; Hilton, Matthew J; Tian, Ye et al. (2011) Teriparatide as a chondroregenerative therapy for injury-induced osteoarthritis. Sci Transl Med 3:101ra93
Sampson, Erik R; Beck, Christopher A; Ketz, John et al. (2011) Establishment of an index with increased sensitivity for assessing murine arthritis. J Orthop Res 29:1145-51
Mooney, Robert A; Sampson, Erik R; Lerea, Jaclyn et al. (2011) High-fat diet accelerates progression of osteoarthritis after meniscal/ligamentous injury. Arthritis Res Ther 13:R198
Wu, Qiuqian; Huang, Jason H; Sampson, Erik R et al. (2009) Smurf2 induces degradation of GSK-3beta and upregulates beta-catenin in chondrocytes: a potential mechanism for Smurf2-induced degeneration of articular cartilage. Exp Cell Res 315:2386-98
Zhu, Mei; Tang, Dezhi; Wu, Qiuqian et al. (2009) Activation of beta-catenin signaling in articular chondrocytes leads to osteoarthritis-like phenotype in adult beta-catenin conditional activation mice. J Bone Miner Res 24:12-21
Wu, Qiuqian; Kim, Kyung-Ok; Sampson, Erik R et al. (2008) Induction of an osteoarthritis-like phenotype and degradation of phosphorylated Smad3 by Smurf2 in transgenic mice. Arthritis Rheum 58:3132-44
Wu, Qiuqian; Wang, Meina; Zuscik, Michael J et al. (2008) Regulation of embryonic endochondral ossification by Smurf2. J Orthop Res 26:704-12
Wu, Qiuqian; Chen, Di; Zuscik, Michael J et al. (2008) Overexpression of Smurf2 stimulates endochondral ossification through upregulation of beta-catenin. J Bone Miner Res 23:552-63

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